Rapid, sensitive and highly specific diagnosis of Moraxella catarrhalis by recombinase polymerase amplification-based biosensor and fluorescence detection

Abstract

Moraxella catarrhalis (M. catarrhalis) was an underestimated respiratory infection pathogen that has been largely overlooked. The limited availability of rapid and sensitive detection methodologies has hindered M. catarrhalis diagnostic in clinical settings and contributed to its underestimation. To address this issue, we devised two recombinase polymerase amplification (RPA)-based assays for rapid, sensitive and reliable detection of M. catarrhalis, termed M. catarrhalis-RPA-Flu and M. catarrhalis-RPA-LFB, which utilized fluorescence and nanoparticle-based lateral flow biosensor (LFB) for reporting the detection results, respectively. In both assays, the specific copB gene of M. catarrhalis was amplified at 37°C for only a period of 20 minutes. In M. catarrhalis-RPA-Flu system, the detection results were analyzed by either using a real-time fluorescent detector or by direct observation using the naked eye under blue light, while, in M. catarrhalis-RPA-LFB system, biosensors were used for interpreting the results without any specialized instruments. Both methods were able to finalize the entire detection process within a duration of 40 minutes, detect down to 35 fg genomic DNA per test, and correctly differentiate M. catarrhalis from non-M. catarrhalis strains. The feasibility of both techniques was validated by analyzing 96 BALF (Broncho alveolar lavage fluid) samples in clinical settings. Collectively, the newly developed two RPA-based assays exhibit great potential for rapid and accurate identification of M. catarrhalis in standard microbiology laboratories as well as diagnosis of M. catarrhalis infection in clinical settings.